Epidemiology Midterm 1

Cumulative incidence (or 'attack rate')

(# new cases occurring in given time period) / (# in population at risk at beginning of time period)

Incidence rate

(# new cases occurring in pop in given time period) / (# in population at risk for the same period) * 10n

Determinant

A collective or individual risk factor (or set of factors) that is causally related to a health condition, outcome, or other defined characteristic. Has to be a cause of the outcome.

Demographic transition

A shift from high birth rates and death rates found in agrarian societies to much lower birth and death rates in developed countries.

Case definition

A standard set of criteria to determine whether a person should be classified as having a disease or condition.

Porportion

A type of ratio in which the numerator is part of the denominator. (Number of people in the population with a condition) / (Number of people in the population)

Rate

A type of ratio where the denominator involves time. Frequency with which an event occurs in a define population over a specified period of time. Example: (Number of deaths among infants aged 1 year or less in 2010) / (Number of live infants born in 2010) * 1000

Scenario: A population of 100 Denver residents aged 80+ were followed from Jan 1 through Dec 31, 2018. None died during the study period and none moved away. None had dementia on Jan 1, 2018. Fifteen were diagnosed with Alzheimer's during the year. Question: What is the cumulative incidence (attack rate) of Alzheimer's for 2018 in this population? A: 15% B: 17.6% C: 85% D: You just lost me!

A. 15%

Which of the following data sources would be the best source for the denominators of cardiovascular disease specific mortality rates? A. Census B. Vital statistics: deaths C. Vital statistics: births D. NNDSS: National Notifiable Diseases Surveillance System E. Cross-sectional survey

A. Census

To study the incidence of chicken pox (a reportable disease) among Denver residents in 2016, which of these is least likely to provide you with representative data? A. Medical records from Infectious Disease Services at Children's and University Hospital B. State records of cases reported by health care providers and laboratories in Denver C. Survey of a random sample of Denver residents

A. Medical records from Infectious Disease Services at Children's and University Hospital

A survey on college professors' health behavior collects a random sample of 1,000 college professors. All of the sampled professors participate in the study. Each professor deliberately skips half the questions, but they truthfully answer the half of the questions that they do answer. What is the major challenge to data quality for this survey? A. The data are incomplete B. The data are not accurate C. The data are not representative D. The data are all good

A. The data are incomplete

In a random digit dial telephone survey, 73% of eligible households who were contacted did not respond to the survey, either because they refused or because they weren't home. What is the major challenge to data quality for this survey? A. The data are incomplete B. The data are not accurate C. The data are not representative D. The data are all good

A. The data are incomplete

In 2016 there were 22,292,911 males aged 15 through 24 and 19,722 of these individuals died during the year. Of these deaths, 6,630 were firearm fatalities, 560 drown, and 5,151 were motor vehicle crash fatalities. There were 278,571 non fatal motor vehicle crash injuries in males aged 15 through 24 in 2016. The case fatality rate for motor vehicle crash injury cases: A: 1.8% B: 3.0 per 10,000 population per year C: 8.8 per 10,000 population per year D: 2.8%

A: 1.8%

A population of 100 individuals aged 80+ were followed from January 1, 2014 through December 31, 2014. On the first day of the study, 25 people had dementia (pre-existing cases). Another 15 were diagnosed with dementia during the year (new cases). None died during the year. What is the ratio of newly diagnosed dementia cases to pre-existing dementia cases in this population? A: 15/25 B: 25/100 = 0.25 C: (15/100)100 = 15% D: (40/100)103 = (40/100)1,000 = 400 per 1,000

A: 15/25

There are 4,552 people living with AIDS in Colorado currently and 1,841 people living with AIDS in Delaware. Which of the following is LEAST correct? A: Colorado residents are more likely to have AIDS than Delaware residents. B: Colorado needs more AIDS case workers than Delaware does. C: Currently there is a higher count of people living with AIDS in Colorado than Delaware.

A: Colorado residents are more likely to have AIDS than Delaware residents.

Population

All the inhabitants of a given country or area considered together.

Outcomes

All the possible results that may stem from exposure to a causal factor. Need a case definition

Risk factor

An exposure that is associated with a disease or adverse health outcome. Not necessarily a cause to the outcome.

Ratio

Any fraction. The value obtained by dividing one quantity by another. Proportions, percentages, and rates are all ratios.

Registries:

Are an important source of cases for case-control studies. Can monitor trends and patterns. May not represent the population and may not have exposure information.

Population of 100 persons aged 80+ was followed from January 1 through Dec 31 (no deaths occurred, no one moved out and no one moved in). On January 1, 25 people had Alzheimer's. Another 15 were diagnosed with Alzheimer's during the year What is the point prevalence of Alzheimer's on January 1? A. 15% B. 25% C. 40% D. 75%

B. 25%

Which of these best describes a high risk approach to the treatment of obesity: A. Implementing a sales tax on sugary beverages B. Encouraging obese patients to get gastric bypass surgery C. Improving sidewalks and bike lanes around the city D. Subsidizing the cost of fresh fruits and vegetables E. Requiring restaurants to post calorie counts for their menu items.

B. Encouraging obese patients to get gastric bypass surgery

Which of the following data sources would be the best source for the numerators of infant mortality rates? A. Census B. Vital statistics: deaths C. Vital statistics: births D. NNDSS: National Notifiable Diseases Surveillance System E. Cross-sectional survey

B. Vital statistics: deaths

On Aug 15, 2018 there were 70 students enrolled in Intro Epi and 10 students dropped the course during the semester. There were 12 students who failed to pass the course with at least a C. What was the incidence of failing to pass the class with at least a C in Spring 2018? A: 12 B: 18.5% = 18.5 per 100 students C: Don't have enough information to calculate this

B: 18.5% = 18.5 per 100 students

A population of 100 individuals aged 80+ were followed from January 1, 2014 through December 31, 2014. On the first day of the study, 25 people had dementia (pre-existing cases). Another 15 were diagnosed with dementia during the year (new cases). None died during the year. What is the proportion of pre-existing dementia cases in this population? A: 15/25 B: 25/100 = 0.25 C: (15/100)100 = 15% D: (40/100)103 = (40/100)1,000 = 400 per 1,000

B: 25/100 = 0.25

In 2016 there were 22,292,911 males aged 15 through 24 and 19,722 of these individuals died during the year. Of these deaths, 6,630 were firearm fatalities, 560 drown, and 5,151 were motor vehicle crash fatalities. There were 278,571 non fatal motor vehicle crash injuries in males aged 15 through 24 in 2016. The cause specific mortality rate for firearm fatalities: A: 1.8% B: 3.0 per 10,000 population per year C: 8.8 per 10,000 population per year D: 2.8%

B: 3.0 per 10,000 population per year

Scenario: A population of 100 Denver residents aged 80+ were followed from Jan 1 through Dec 31, 2018. None died during the study period and none moved away. Fifty had already been diagnosed with Alzheimer's by Jan 1, 2018. Fifteen more were diagnosed with Alzheimer's during the year. Question: What is the cumulative incidence (attack rate) of Alzheimer's during 2018 in this population? A: 15% B: 30% C: 50% D: 65%

B: 30%

Determinants can be:

Biological (bacteria, viruses), chemical (carcinogenic chemicals), or even social or behavioral (smoking, food consumption, lack of exercise, living in poverty)

First step in addressing a public health problem is to document its:

Burden (how many people are affected) and risk (how likely is it that any individual will be affected)

If the U.S. Vital Statistics mortality data sometimes misclassifies deaths of Hispanics as deaths of non-Hispanics, then what would happen to our estimated crude death rates for the U.S. population? A. The CDR would be too high B. The CDR would be too low C. There would be no impact on the CDR * Crude death rates (CDRs) and crude mortality rates (CMRs) are the same thing.

C. There would be no impact on the CDR

Which of the following best describes incidence? A: 23 of 100 day care students caught pertussis B: 23 of 100 day care students had pertussis on the first day of class C: 23 of 100 students caught pertussis on the first day of class D: 23 of 100 students either had pertussis or caught pertussis on the first day of class

C: 23 of 100 students caught pertussis on the first day of class

Scenario: A population of 100 Denver residents aged 80+ were followed from Jan 1 through Dec 31, 2018. None died during the study period and none moved away. Fifty had already been diagnosed with Alzheimer's by Jan 1, 2018. Fifteen more were diagnosed with Alzheimer's during the year. Question: What is population at risk of being diagnosed with Alzheimer's on Jan 1, 2018? A: 100 B: 85 C: 50 D: 15

C: 50

In 2016 in the US there were 22,292,911 males aged 15 through 24 and 19,722 of these individuals died during the year. Of these deaths, 6,630 were firearm fatalities, 560 drown, and 5,151 were motor vehicle crash fatalities. There were 278,571 non fatal motor vehicle crash injuries in males aged 15 through 24 in the US in 2016. The crude mortality rate is: A: 1.8% B: 3.0 per 10,000 population per year C: 8.8 per 10,000 population per year D: 2.8%

C: 8.8 per 10,000 population per year

Case registries

Centralized database for collection of information about a disease or condition.

Good data must be:

Complete - very low rates of missing data Accurate - reflect what we are trying to measure Representative - generalize to some broader population

Exposure

Contact with a disease causing factor or the amount of the factor that impinges on a group or individuals. Related to determinant.

Which of the following data sources would be the best source for measuring the numerator of an incidence rate for measles? A. Census B. Vital statistics: deaths C. Vital statistics: births D. NNDSS: National Notifiable Diseases Surveillance System E. Cross-sectional survey

D. NNDSS: National Notifiable Diseases Surveillance System

In 2016 there were 22,292,911 males aged 15 through 24 and 19,722 of these individuals died during the year. Of these deaths, 6,630 were firearm fatalities, 560 drown, and 5,151 were motor vehicle crash fatalities. There were 278,571 non fatal motor vehicle crash injuries in males aged 15 through 24 in 2016. The proportional fatality rate for drowning: A: 1.8% B: 3.0 per 10,000 population per year C: 8.8 per 10,000 population per year D: 2.8%

D: 2.8%

Data available on the CDPHE website shows in 2013 of the 9,316 total live births in Denver County 15 children were born with cleft palate without cleft lip and of the 1,859 live births in Pueblo County 3 children were born with cleft palate without cleft lip. What was the prevalence of cleft palate without cleft lip in Pueblo County newborns in 2013? A: 0.16 cases per 100 newborns B: 1.6 cases per 1,000 newborns C: 16.1 cases per 10,000 newborns D: all of the above are correct

D: all of the above are correct

Secondary data

Data that someone else has collected previously. Often cheaper and faster, you may have a larger sample size, and you might be able to follow trends over time. May lack the information you want from the population you want.

Primary data

Data you collect. Collect the data you want, from the population you want. Is expensive, time consuming, ma necessitate smaller samples, and may be difficult to continue over time.

Cause-specific mortality rate

Describes everyone in the population who died from a specific condition that occur during a specific period. (# deaths from specific disease in time period) / (total population) * 10n

What can counts be used for?

Determining overall impact (burden), determining resource needs, tracking rare conditions and outbreaks, and reporting unusual presentation

During the 2012/13 academic year an injury surveillance system implemented in a large national sample of US high schools captured the following number of concussions in boys sports: 878 in football, 96 in boys' basketball, 88 in boys' soccer, and 38 in boys' ice hockey. Which sport has the lowest risk of concussion? A: Football B: Boys' basketball C: Boys' soccer D: Boys' ice hockey E: Can't tell based on data provided

E. Can't tell based on data provided

According to the demographic transition theory, population growth occurs because of:

Failing mortality over time

The natural history of a disease refers to the process of a disease among those who are receiving medical treatment for their condition.

False

What things decrease prevalence?

Fewer cases of disease, short duration of disease, and large population at risk.

Surveillance systems:

Generally emphasize prevention and control. Usually population based, although not all cases show up in surveillance systems. May provide limited detail or accuracy.

Sources of public health data:

Individual data, health care provider, and other entities

What factors can affect prevalence?

Infection rate: how many of those exposed to an infectious agent will become infected? Morbidity rate: how many infected people will show signs of being sick? Duration of symptoms: how long people are sick? Mortality rate: how many people will die?

Secondary prevention

Limits the progression of a disease in early stages of pathogenesis

Fixed population

Membership is permanent and is defined by a "life event."

Dynamic population

Membership is transient and defined by changeable condition.

What things increase prevalence?

More cases of disease, longer duration of disease, and smaller population at risk.

Percentage

Mostly used to express proportions. A ratio (fraction) expressed in % format, meaning with the denominator set to 100.

Are counts alone the best way to compare health conditions across different populations?

No! You also need to know the size of the populations at risk. Cannot be used to compare risk

Case fatality rate

Not actually a rate. Proportion of those with the disease who die from it. Describes the 'killing power' of a disease. (# deaths due to specific disease) / (# people with that specific disease) * 100%

Count

Number of cases of a disease or other health (condition) being studied. Usually in a specific population. Usually negative health outcomes.

Prevalence

Number of existing cases of a disease or health condition in specified population at some designated time. (# of cases in pop at specific time) / (total # in pop. at specified time) * 10n

Incidence

Number of new cases that occur in a population at risk in a given period of time. Likelihood of new cases occurring during a specified time period. Occurrence of disease in a population (new cases)

Lifetime prevalence

Period since birth. Health condition of interest existed at any time during a person's lifespan

Other entities can also provide data:

Physical environment (water, air), financial data (tobacco sales, tax records), educational or court records, and more

Primary prevention

Prevent disease before it occurs

Three prevention strategies

Primary prevention, secondary prevention, and tertiary prevention.

Quantification

Refers to counting of cases of illness of other health outcomes.

Health care provider data can come from:

Reviews of records (medical records, billing records), state or national reporting systems (reportable or notifiable conditions)

Population approach

Seek to have a broader impact by reducing the distribution of risk in the population, rather than treating individual patients

Tertiary prevention

Seeks to restore a patient's optimal functioning in the later stages of pathogenesis

High risk approach

Seeks to treat the individuals (patients) who come into their office, often because they already have health problems

Individual data come from:

Self-reports (surveys, interviews, focus groups), public observations, or other measurements (mobile devices, biomarkers)

Crude mortality rate

Specific type of incidence rate describing everyone in the population who died. Number of deaths that occur during a specified period of time in the reference population. (# of deaths in pop during time period) / (total population) * 10n

Public health surveillance

Systematic continuous gathering of descriptive information about health conditions and their determinants

Epidemiologic transition

The changing patterns of morbidity and mortality as the rates of death fall throughout the demographic transition. Declines in maternal and infant mortality result in increase life expectancies. The share of deaths from infectious and parasitic diseases declines.

Natural history

The natural history of disease refers to the course of a disease from its beginning to its final clinical endpoints. Refers to the progression of a disease in the absence of treatment.

Risk

The probability of an adverse or beneficial event in a defined population over a specified time interval

Proportion Mortality Rate (PMR)

The proportion (actually reported as percentage) of all deaths in a population due to the specific cause of interest. (# deaths due to specific disease) / (# total deaths) * 100

Point prevalence

The proportion of the population that has the health of outcome of interest at a specific point in time. A "snapshot." (# cases existing at a specific time point) / (total population at the specified time point) * 10n

Period prevalence

The proportion of the population that has the health outcome of interest within a specific time period. (# cases existing during specified time period) / (total population during the specified time period) * 10n

Epidemiology

The study of what comes upon people. Concerned with the distribution and determinants of health and disease, morbidity, injuries, disability, and mortality in populations. Epidemiologic studies are applied to the control of health problems in populations.

Population at risk

a group of people who share a characteristic that causes each member to be susceptible to a particular event (i.e., disease or condition)

Population growth occurs...

because mortality declines while fertility stays the same at a high level. Mortality rate declines first, fertility rate stays the same, then declines later.